I am always interested in capturing real values via hardware devices in order to generate the appropriate graphs with my monitoring system. Of course, the outside temperature in our city was at the pole position for such a project. Therefore I ordered a few temperature/humidity sensors from PCsensor (via eBay), plugged them via USB on my Raspberry Pi (Raspbian Linux), and queried them via SNMP from my MRTG/Routers2 monitoring server. Here is the whole story: